Mulches not created equally.
COLUMN: ROOTS OF WISDOM
When gardening experts suggest that you mulch your plants, do they warn you about bad mulch? Make no mistake. The concept is valid, but it is the execution of the process that can cause problems.
Begin with the knowledge that in most instances mulching plants is an excellent practice. A problem may arise from the fact that all mulching materials are not equally beneficial. When mulch was first offered, it was composed of tree bark. It may have been from pines, hemlocks, spruce or even redwoods. The shredded bark was a byproduct of the lumbering industry.
When a log entered the mill, the first step in the production of beams or boards (dimensional timber, two by fours or such) was to remove the tree bark. The bark was removed mechanically by knives that stripped the bark from the log. The shredded bark was blown out of the mill into a waste pile.
Then a comparatively few years ago, the discovery was made that this bark waste had a use in the landscape. It could be used to suppress the growth of weeds, prevent the loss of water from evaporation and help stabilize the root environment. As it was derived almost exclusively from evergreen trees, conifer bark had added advantages in the landscape because it does not support the development of insects and diseases. This was due to natural chemicals in the bark (tannins and other chemicals) that were produced by tree bark to prevent invasion of the living tree by various pests.
Fast-forward a few decades to now, when this waste product is no longer a waste product but rather a widely used component of most designed landscapes. Only in this country is mulch used to the extent we commonly see it deployed around us. Look in vain to see it used in the gardens of England, Ireland, Europe or Asia.
The use of mulches is so common that there is not sufficient waste bark to satisfy the demand. Thus, we are offered whole trees (often scrub trees worthless as lumber) that are chipped or ground and dyed a "redwood" color to improve its marketability and hide its humble origins.
As a response to increasingly strict regulations as to what can go into landfills, all manner of waste, including construction debris, wood scraps or no-longer-serviceable pallets, are being offered as "mulch" to the public.
Note that none of these materials has the natural resistance to decay or invasion by pests that is present in true bark mulch.
Wood chips from regular tree trimming are easily identified as to origin. After being allowed to rot for a year, they make an excellent soil amendment or surface mulch. Summer prunings break down more rapidly than winter wood chips, as they contain no quickly decomposable leaves.
Know what you are buying and choose well.
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|Publication:||Telegram & Gazette (Worcester, MA)|
|Date:||Jun 9, 2013|
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